This invention relates to a self-closing discharge valve for use in a pressurized container from which a liquid product is to be dispensed, with the aid of a propellant, in liquid, pasty or foamy condition, which valve opens automatically when an external part thereof is moved in a given direction.
Such valves are numerous, but show certain drawbacks. They require usually a plurality of parts, among them at least one spring which is usually made of steel wire. Moreover, from many of the known valves, product such as a shaving lather foam, is ejected suddenly in an undesirably large quantity, especially in the initial stages of using a new pressurized can, while the propellant pressure inside the can is still high.
Also, in many cases it is practically impossible to empty the can completely from product stored therein. In other cases, it is not possible to obtain a product discharge when the can is held in upside down position.
A poppet valve comprising only two parts, namely, a tubular outer nozzle member having a flexible wall zone in its central region, and an inner, rigid valve stem, an obturating poppet head at the inner end and prongs forming anchoring means, at the outer end of the stem, has been described in U.S. Pat. No. 2,954,903 to Collins, and a similar patent further comprising a bellows in the said flexible zone is described in U.S. Pat. No. 2,975,944 to Michel. In these valves the poppet head may not free the entry passage from the interior of the pressurized container into the tubular passage in the nozzle member, especially when higher excess pressures of up to 10 bars prevail in the container unless there is applied a very pronounced angular deflection of the nozzle member.